[jdkJake]

Quote:

the PS supply schematic in the BOM linked above and here:
http://www.cavalliaudio.com/ehhaa/main.php?page=schematics/powersupply
 
have L2R and R6R in a different order from ground to the negative rail. It would seem that the one in the quoted link is correct.
 
When you use the bottom side trace between the two parts to decide which way to orient the the LED, it means that you get a LED installed backwards if you use the website version.

Aha! Mystery solved.
 
Nice catch cobaltmute.
 

 

[sachu]

I think I am just going to modify the values in the heater circuit and only build one of the boards up for 12.6 V and wire it up in series. Just seems to make more sense to me. 

 

[MrSlim]

Has anyone compared the SQ of the 6GM8 to the 6922 in the RevA or the original EHHA?

 

[sachu]

i have tried the 6DJ8 in the amp and its alright. 6GM8 sounds better.

 

[MrSlim]

Thanks Sachu, have you thought about what you are going to use for casing?  What's the height measurement to the top of the highest component on the board (the tube?) (with board standoffs)?

 

[stixx]

Heatsinks are 2", so incl stand offs and the pcb itself you are probably looking at around 65mm...
With tube it will be slightly higher... I seem to recall that someone here wanted to use a 70mm case (sachu?) that just barely would fit.

 

[sachu]

You should be able to fit it in a 3 inch tall par-metal case without too much of a problem if you stick to 6GM8 tubes. Use 5mm standoffs and you should be plenty fine.

 

[cobaltmute]

I believe my stand-offs are 6mm and with the 6n27P, total height is 2 7/8"

 

[MrSlim]

So, is there any consensus on whether E12's are recommended for headphone protection?

 

[jdkJake]

So, is there any consensus on whether E12's are recommended for headphone protection?

I don't believe there is a consensus yet. It will probably remain an optional addition to the build. Just be aware of the potential issues involved by not using it. Also be aware, to do it right, you need two of them, which can drive up the cost of the build significantly.

FWIW, I am going to use them on my builds. I see it as a value added proposition. I have all the parts, just need the time. Right now, professional sports in Tampa Bay have been providing considerable distraction (shameless plug for Bolts/Rays/Bucs!)

 

[runeight]

Why would you need two?

 

[johnwmclean]

 
 
Quote:

The ε12 must be powered from the amplifier's main power supply rails. Do not use a separate power supply for this circuit. If your amplifier has a separate power supply for each stereo channel, you should use two ε12 boards. Each one serves one channel only, and is powered the respective supply rails.
 
AMB

 
 
Since each channel on the new EHHA revision has it’s own psu you’d need two.

 

[cobaltmute]

I'd use two no matter what due to the fact that the e12 sums the offsets of each channel.  If the rails go south in opposite directions, the e12 will never notice.

 

[jdkJake]

I'm just glad they are small. My selected case is starting to fill up fast!

 

[cobaltmute]

They'll fit in a 12x12 Par Metal.  I've been sizing it out.  It is tight, but they will fit.